U.S. Pat. No. 4,885,826 (Strudel), filed Sep. 29, 1988, and corresponding to German Patent 3,732,754 discloses a circular spreader for tubular textile fabric in which the central support shaft comprises two sections capable of telescoping relative to each other. A clamping mechanism is arranged inside the telesscoping sections of the spreader. The clamping mechanism is rigidly connected with the inner tubular section of the central support shaft on the one hand, and connectable in a force and form locking manner with the inside of the outer tubular section of the central support shaft. The clamping mechanism includes a clamping device that is connected to a connecting element with the upper bearing or support section of the head portion of the circular spreader. Thus, when the two tubular sections of the central support shaft are pulled apart in the axial direction, the clamping device is activated in such a manner that a further pulling apart of the tubular sections forming the central support shaft is prevented under normal operating conditions.
Such a clamping device, however, leaves room for improvement, especially with regard to providing an operational stability even under adverse operating conditions, for example, when uneven characteristics of the tubular fabric, such as a seam, expose the circular spreader to vibrations or even shocks. Such vibrations and/or shocks or impacts can temporarily reduce or even eliminate the frictional contact between the clamping components of the clamping device on the inner surface of the inner tubular section of the central support shafts. As a result, pressure spots may be formed in the tubular fabric by the position maintaining rollers of the roller heads. Such pressure spots reduce the quality of the tubular fabric. The position of the clamping device inside the tubular sections of the central support shaft also leaves room for improvement, because such a location of the clamping device does not facilitate the inspection and maintainence of the clamping device. Thus, when the clamping device needs to be repaired, the entire circular spreader must be taken apart.